Embodiments of the present invention relate to thermal management of microprocessors and more specifically to optimize frequency and performance in a multi-die microprocessor via a serial link replicating states across the multiple dies.
In a multi-core microprocessor, it may be desirable to allow the cores to use available power headroom to maximize performance. In such instances, the cores may operate at frequencies and/or voltages above those specified by the manufacturer. Thermal throttling may then be used to reduce the operating frequency and/or voltage of the cores when a target temperature is reached or exceeded.
However, thermal throttling may not occur in some environments, such as where the ambient temperature is sufficiently low. In such an environment, there is no mechanism available to reduce the operating frequency and/or voltage, and the processor will be permitted to run at a frequency/voltage greater than specified by the manufacturer for an indefinite amount of time. In this case, the power delivery system must be over-designed in order to supply the additional power required for the system.
With the progress toward multi-die processors, each die can not readily ascertain the status of the other dies with respect to an idle or active status. Consequently, this precludes setting an optimal frequency and performance for the multi-die processor. One inefficient solution is routing dedicated signal lines to transmit and receive core power status. Unfortunately, the cost of this solution is directly proportional to the number of cores as well as the number of core power states.